.3 


AN  INVESTIGATION  ON  THE  PRODUCTION  OF  LEAD 
ARSENATE  BY  ELECTROLYTIC  METHOD 


BY 


ARATA  LEO  NITTA 


THESIS 

FOR  THE 

DEGREE  OF  BACHELOR  OF  SCIENCE 
IN  CHEMISTRY 


COLLEGE  OF  LIBERAL  ARTS  AND  SCIENCES 
UNIVERSITY  OF  ILLINOIS 
1922 


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THIS  IS  TO  CERTIFY  THAT  THE  THESIS  PREPARED  UNDER  MY  SUPERVISION  BY 


ENTITLED. 


IS  APPROVED  BY  ME  AS  FULFILLING  THIS  PART  OF  THE  REQUIREMENTS  FOR  THE 
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ACniOwLEIiG-LIEIIT 


To  Professor  I'utnum, under  Yvhose  direction  this 
investigation  'jvas  carried  out,  the  writer  wishes  to 
express  his  gratitude  for  many  valuable  suggestions 
and  kind  guidance.  Thanks  are  also  due  hr.  hiet- 
ricson  , T;ho  by  furnishing  necessary  apparatus,  has 
made  the  laboratory  work  possible. 


Digitized  by  the  Internet  Archive 
in  2015 


https://archive.org/details/investigationonpOOnitt 


liJTROi^UCTIOK. 

The  electrolytic  process  is  a recent  advancement  on 
the  manufacture  of  various  pigments  and  some  chemicals, 
x-ef  erences : - 

’'The  i.i£,nufac tur e of  Chemicals  by  Electrolysis"  by  x-.. 
y • Hale . 

"Electrolytic  production  of  Yvhite  lead,  cadmuim  yel- 
lo7/,  of  murcury  vermillion,  of  ^icheele's  green,  and  of 
Eerlin  blue,"  in  “x^perimentalElecti  ochemistry"  by  rxop- 
kins , pp.  I£E-  i32. 

-several  patents  have  been  grantedon  the  manufacture 

of  Yvhite  leadby  electrolysis. 

u . S . 644 , 7 7 6 1 19  uO ; by  huckOYv . 

"fin  Electrolytic  xrocess  for  xvxanufacture  of  .-'hite 
xjead"  , by  .iilliams,  -Rm.  9hem. xjOc  . ( 189  5 ) p.8a5. 

Y "xrocess  of  -i.ianuf.  -ixead  salts  b^  electrolysis 
U.S.  67  5,  455U90rjby  d.  B.  Tibbits. 

"liethod  of  x.xanuf . of  eeed  salts  by  electrolysis 
U.  X..  1?  306,948  by  e.  narringt oni  1919  i . 

"..hite  x.eo.d  by  xjlectr olysis " by  n.?x . Bro'wn. 
u.  e.  496,r09  and.  56a,  555. 

^^nd  several  others. 


-2- 


It  is  claimed  that  the  electrolytic  production  of  vihite 
lead  has  a great  advantages  over  the  old  proeer:ses  of  nutch, 
or  -rench,  o_  the  '-^arterS. 

V/hy  then  the  similar  process  can  not  be  applied  on  the 
production  of  lead  arsenater 

The  inve^. tigation  involves  technical  process  based 
upon  the  chemical  theories  and  the  vvhole  success  moreover 
depends  upon  the  economical  standpoint  o_  the  manufacturing . 
in  attacking  tho  problem  it  is  veil,  hovever,  at  the  first 
hand  to  consider  the  successful  production  o:  lead  arsenate 
vithout  considering  all  the  economical  factors  involved. 

After  finding  the  favorable  cojnditions  of  itsmanufacture 
the  economical  features,  such  as  the  cost  of  rav  materials, 
amount  of  energy  to  be  consumed, the  cost  oi  labor  for  the 
production,  and  the  conditions  should  be  considered, 

I'he  sphere  of  the  vork  is  vide  and  it  requires  a 
profound  knovlvdge  of  electrochemistry  coupled  with  an 
ability  in  doing  researches. 

my  work  is  simply  a preliminary  survey  on  the  sub- 
ject ‘and  1 leave  this  work  undone  to  a promising  electro- 
chem.ist,  r;ho  may  happen  to  bump  on  this  stumbling  block 
in  some  future  days, 

i'he  main  influencing  conditions  on  the  process  to 
be  investigate  are  the  f ollowings : - 

1.  I'lature  of  the  electrolyte, 

2.  concentration  of  electrolyte  u.:ed. 

5.  xemperature  influences  under  which  tfie.  process 


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is  worked. 

4.  .suitable  materials  for  the  electrode. 

5.  >^iiitable  electrode  area  and  current  density. 

6.  iniuences  of  electrode  portentials. 

7...  Specific  gravity  of  electrodes  before  and  after 
the  electrolysis. 

8.  x^ature  oi  the  precipitates  obtained. 

9.  Economical  investigation  on  the  process,  etc. 


j.iiix  C2'TiinCiij  Uii’  i.i'i  kjjLjC • 

Cult ivc^tc d plL^nts  are  blvvays  more  susceptible  to  dis- 
ec.se  and  are  attacked' by  incects  than  are  the  Vv'ild  plants. 
The  more  highly  developed  become  our  a^ricultuaip- oduc ts 
the  more  care  i.-.  necessary  to  protect  them  from  agencies 
which  will  hinder  their  gro\;th.  rhi..  ic  the  reason  tha 

the  manufacture of  agricultual  insecticides  and  fungicides 
has  become  the  highly  important  industry. 

Classes  ox  .iii'd  ihox.Ci]iOlJJij 

There  s-ire  two  classes  of  insects;  one  ii.  chewing 
insectsand  the  other  is  sucking  in..ects.  ^hewing 

insects  bite  or  chew  the  foliage  or  fruit  until  they  act- 
ually . destroy  the  plants.  tiaterpillers  o;.  all  kinds, 
beetles  and  cut  worms  are  this  type.  These  che'wing 

inoects  are  killed  most  easily  by  Lpraying  the  poison, 
u'.ually  ar.  enic  compounds,  oyer  the  plants.  x-or 

this  purpose  lead  arsenate,  and  recently  calcium  ar.,  enate 
are  most  successfully  used. 

TO  the  latter  class  of  insects  belong  various  mites 
or  scales  and  plant,  lice.  X’or /insecticide  ox  this 

class,  it  ic  necessary  to  use  .:ome  materials  which  v.ill 
killby  coming  in  contactwith  the  body  of  the  insect, 
hicotine  sulfate  , lime  sullur 


and  some  othbrs  are  used 


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Kixli  Oxu^  u li'.  01:'  Ut-'xj  Oi}'  J.is  Kj  vJ ’J?X  O -LLi  Ij1\  X 'i'1-.lJ  »j  Xii.  i.'i-ii-' * 

X'he  insecticide  business  got  its  reaX  start  when 
'the  ooXoro-do  potato  beetXe  took  up  its  ^journey  eastward 
and  began  infesting  the  potato  fieXdin  the  eastern  part 
of  the  country.  J-t  i found  that  aceto-  arsensfce  of 

cop>per  or  -faris  green,  whiich  is  used  as  a green  pigment, 
couXd  be  used  on  tlie  potato  vines  with  good  effect. 

• 9 

Oonsiderabie  success  Y/as  met  with  and  befor  Xong  tb.e  use 
of  arsenic  compounds  in  paint  became  unpopuXar  and  Y^arious 
chrome  greens  took  tlieir  place  with  the  resuXtt  that  for 
many  years  tlie  production  of  raris  green  has  been  practical 
ly  for  . insecticide  use  only.  s^radually  tliis  ..was 

tried  for  another  plants  , but  the  soluble  portion  of 
tXie  arsenic  was  absorbed  by  tlie  plants  and  burning  effect 
on  plant  v.'as  marked. 

At  tlie-  time  of  the  gipsy  moth  outbreak  in 
iviassachusetts , it  Yvas  suggested  that  arsenate  of  lead 
contained  very  little  v^ater  solubleax'oenic , might  be 
used  to  advantage.  it  was  tried  out  and  , found 

suitable  in  many  Yvays  for  this  purj^ose.  hesiaesb 
being  insoluble  and  tb.us  practically  harmless  to  very 
tender  foliage,  it  also  had  another  a'dvantage  over 
la.ris  green  in  that,  in  its  linely  devided  form  after 
drying  from  the  sprs.y  soj.ution,  it  adheres  to  the  leaves 
and  was  not  readily  washed  of.J  by  the,  rain,  ^irsenate 


of  lead, hence,  grew  in  popularity. 


j-t  could  be 


usea 


-6- 


on  neary  all  foliages  without  donger  of  burning  and  v;ould 
cling  to  the  vines  or  to  the  foriage  through  several  rain 
storms,  and  has  a high  killingn  power. 

bTjiUiii  Ci'  i.uh'i Lh ^j.C TUxLij  Gi 

ari~enaoe , useu  up  do  -lGOG  , was  pi'epareo.  at 
home  by  each  user  without  much  or  any  chemical  knowledge 
mostly  by  mixing  the  solutions  of  sodium  arsenate  and  lead 
acetate.  ''ihis  precipitated  lead  arsenateand  the  whole 

mixture  was  then  poured  into  the  spray  tank  for  the  use. 

IhlTI^J.  IhbaCflClhli  IhLUbfRY. 

The  first  successful  commercial  manufacture  was 
carried  out  by  Gornelius  h.  Yreeland  of  iviontelair,  h.  J. 

In  February,  ±906, he  made  application  lor  a patent  covering 
an  electrolytic  method  of  preparing  ar- enic  compound  of  lead, 
U.  0.  870, 9i£  (1906) 

for  s veral  years  his  " hlectro  " brand  manufactured  in  a 
little  plant  in  I'otowa  just  outside  of  rat  ter  son,  i. . J.  was 
the  be.  t known  in  the  market.  I'he  process  was  , how- 
ever, abondoned  by  his  firm.  ■ 

rhe  method  of  precipitation  of  lead  arsenate 
by  sodium  arsenate  and  lead  acetate,  wlilch  wasv  then  being 
by  several  small  x^lants,  was  expensive.  ^irsenic 

acid  and  litharge  are  fairly  cheap  raw  materials, 
iixtensive  experiment  on  the  use  of  the  said  compounds  start- 


-7- 


ecland  _inally  came  out  as  a commercial  product. 

Cliom.  Let.  ■^ng.__24,  I19k<lj  1.  o<ol. 

±n  1909,  K.-O.  ^uther  and  . K • Volck,  of  Watsonville, 
California,  obtained  a patent  on  tke  manuiacture  oi  lead 
arsenate  by  mixing  arsenic  aci5.  and  litliarge. 
u.  b»  9f9,96E,  iiug . o,  1909. 

'ilie  mixture  was  roasted  in  presece  of  oxygen  assitted  by 
oxydizing  agent.  -^-ead  arsenite  , formed  at  tke 

eary  stageb,  is  oxydized  into  arsenate.  ^ince  that 

time  more  than  a dozen  patents  are  taken  out 'on  the  supject. 

xi.pprox;imat e chemical  composition  of  commercial  aisencute. 

Thre  rae  several  kinds  or  laed  arsenate  possible. 

'i'he  original  product  was  vhat  is  knoir.n  as  a Griplumoic 
arsenate  of  lead,  O4 

theoretically  it  contains 

74.4E  percent  of  xb  0. 

E5.58  " ” 

and  the  other  is  orthoplumbic  arsenate,  v;hich  contains 
theoretically 


64. S8  percent 

of 

xb  0 

55.13 

£.59 

” K;,0 

-4m.  bhem.  80c. 

11915) 

X.  1685. 

•-  a 


-8- 


commercial  lead  arsenate  is  a mixture  oi  the  above 
tv.o  forms  in  different  propoi-tions ,and  this  variatipn  in  the 
proportion  due  to  the  different  methods  of  preparations, 
file  value  of  the  insecticide  is  determined  by  the  amount  of 
arsenic  in  the  compound;  and  some  of  the  best  grade  contains 
up  to  50  per  cent  of  arsenic  oxide. 


By  the  Insecticide  and  Fungicide  Act  of  1910,  the 
paste  form  of  lead  arsenate  should  not  contain  more  than 
50  percent  of  vvater.  rt  should  contain  at  least  12  l/2 

per  cent  of  arsenic  oxide,  and  less  than  s/4  of  one  percent 
of  arsenic  oxide  in  water  soluble  form. 

Chem.  Age,  (1951^  no.  7,  p.  257  . 

'I!  fxOCxJOS  01'  flilv  Oi ACT Ui till  CF  ABr  i'.Aji  iXi-J.— >1A1ju  > 


fhe  larger  part,  probablymore  than  three  fourths 
of  the  arsenate  of  lead  .produced  in  this  country,  is  made 
by  the  interaction  of  arsenic  acid  and  litharge. 

'i'herej  are  t’v^o  distict  methods  of  manufacturing  • - 
one  being  a 'wet  process  and  the  other  , 'which  is  rather 
a recent  invention,  being  dry  method, 
fry  methods'. - 

8.  2:  1,544,055  I 1920 j by  1.  Eedenburg 
and  f*  2*  fx’att . 

b.  2.  1,17  5,565  by  n.  2hepherd,  1 1916 J 


-9- 


ind.  and  o^ng.  Chern.  lb,  (19211  p.  551. 
ilie  ra\7  materials  commonly  used  , due  to  the  cheapness 
are  litharge  and  white  arsenic.  wome  processes,  howerver, 
claim  certain  advantages  in  using  lead  nitrate  , white  lead, 
lead  peroxide,  and  lead  acetate. 

Current  Quotations  on  rrices  of  haw  Ivlaterials  Used. 


by  carlot  less  carlot 

nitharge  per  lb.  0.07  I/2--.O8  .081/e--.09 

■.ihite  arsenic  " . O6---.06I/4  .06  1/e--.o7 

nead  nitrate  ” . .15 .20 

^ead  acetate  " .10  5/8--. 12  1^ 


head  arL^enate  i paste  .09--. 09  1/2  .010 .0.11 

i^ead  arsenate  ” .06  l/ 2 .o7  .07  1/2-.O6 

I in  powder/ 

uodium  nitrate"  .025  .026 

Ohem.  het . -^^ng.  Oiiipt.  1921. 

•jodium  arsenate  per  lb.  0.76 


Quoted  from  price  li^t  of  Hillinckrodt  Ohem- 

ical  .-orks  Q921i 

8odium  arsen'ate  0«  1.  per  lb,  yO.52 
j.  B.hake:^  Chemical  company. 


-10- 


'•'lii \ 

^ij'ps.ratus  u>:  ed , - 

iinipmeter-- west  on  direct  reading:  ampmeter,  hi'.vinp 
rea0-in£,  ox  x«3  a*-*piiieterx’  • 
ivheos tat --(Carbon  rheostt-t. 

Toltmeter-rreston  direct  cu.rrent  voltmeter  having 
5 ang  10  volts  oi  reading. 

^l;.ctrodes  used--v-arbon , iron,  lead,  ana  copper. 

Cell  iar--  One  liter  beaker  is  used. 

-diaphragm--  porous  porcelain  cup. 

iource  OI  electricity — xrorn  110  volt  direct  current, 
kiagreim  of  a,H;'aratus . 


-11- 


i~*iA  -L  Hl  XIkjJ  *1^]  1 1* 

Ihe  first  epperiment  based  upon  the  theory  of  preci- 
pitation of  insvoluble  lead  arsenate  in  contact  with  arsenate 
ion  from  soluble  arc-encite  salts  with  lead  ion  electrolytically 
set  free  from  the  lead  anode.  i‘he  commonly  known  salts 

such  as  sodium  arsenate  and  sodium  biarsenate  are.;  tried. 

ihe  different  kinds  and  different  concentrations  of 
electrolytes,  various  electrodes,  and  the  effects  upon  the 
precipitation  with  various  curi'ent  densities  were  tested. 

ihe  following  experiments  were  performed  under 
fixed  conditions  only  varying  the  electrolyte  and  its  con- 
centrations. 

Ihe  fixed  conditions  are 

klect :|iodes , -*-^athode , - Cu  rlate  whose  area 
being  l.V  dm.  sq. 
i:..node  , --xb  . plate  v;hose  area  being 
2.6  dm . s q . 

Current  density,-  0.5  amp.  per  sq.  dm. 
■temperature,-  -o.t  room  temperature. 

Duration  of  run,-  30  minutes, 

Ei.periment  1. 

rllectrode  used  ,-  sodium  biarsenate. 

Concentration,-  5 per  cent  solution. 

Observation, - 

■uydrogen  gas  from  the  cathode, 
uxygen  from  the  anode. 


-12- 


iio  precipitate  Vvas  obtained. 

i!it;periinent  2. 

Electrode  used,-  Sodium  arsenate. 

Concentration,-  5 per  cent  solution, 
observation  ,- 

evolution  oi  tlie  gases  as  in  the  preceding  exp. 
ho  precipitation  was  obtained. 

Experiment  3. 

Eliectrolyte  used,-  Codium  biarsenate, 
ooncentration, - 10  per  cent  solution, 

observation. - 

oame  as  the  precedings. 

-experiment  4. 

-electrolyte  used,-  oodium  arsenate, 
ooncentration, - 10  per  cent  solution, 
observation,-  oame  as  the  precedings. 

ihe  affect  of  secondary  *jalts. 

'fhe  effect  of  the  presence  of  secondary  salt  in  iiie 
electrolyte  was  tested,  as  it  was  suggested  by  o*  i'.  Carrier. 
He  succesfully  used  sodium  chlorate  or  sodium  acetate  in 
the  preparation  of  white  lead  from  sodium  carbonate  solution 
with  lead  anode. 

■J.  -^'hys . ohem.  ^1909;  3^,  -i-p.256  and  3o2. 


-13- 


-LTans.  -L:^lectro.  '-^hem.uoc.  il904;  p.  229, 

u,  S.644,  779  ly  xacliard  and  iloepper. 

iixperrment  5. 

^'’lectrolyte  used,- 

50  parts  oi'  5 per  cent  of  sodiua  arsenate 
50  " '•  ” " ” " sodium  chlorate 

ubservation, - 

Oases  from  the  both  electrodes, 
ho  sign  of  precipitation. 

Experiment  6. 

xilectrolyte  used,- 

50  parts  of  5 per  cent  ol  sodium  acetate. 
50  2 " " ■'  souium  arsenate 

ubservation, - 

^ame  as  the  preceding. 


ifeperiment  7 , 

electrolyte  used,- 

20  parts  of  5 per  cent  o_  sodium  arsenate 
40  ■■  " " “ ” sodium  acetate. 

40  " " " " sodium  chlorate. 

Observation, - 

eame  as  the  preceding. 


-14- 


Summary 

ox  experiment 

e-eries 

1. 

exp . 

Electrolyte 

, eoneent. 

ulservation.  Precipitation. 

1 

x^ia^  n As 

5/0 

sol. 

uases  evolut . no. 

from  electrodes. 

2. 

i'ia^-ii-s  0^ 

5 7^ 

sol . 

«( 

2. 

na^A  asu^ 

10  70 

sol . 

( < > * 

4. 

i^a^As 

10  7^ 

sol . 

II  )• 

5. 

^ parts  of  ix 

a^-^s 

5 70. 

50  *■  " l^a.^1  5 /o. 

6.  50  parts  of  i^aAs  5 7*?. 

50  ~ " i^a  COUCH  5 'jo 

7.  20  pts.  of  iiaa^is  L-v 

40  ■'  “ Ka  oOuCH 

40  " '■  -tia  CLO3 


-15- 


I'he  conditions  being  the  same,  the  effect  on 
various  concentrations  of  electrolyte  -was  tested. 

rsperiment  1. 

i:ilectrolyte , -500  CG.  Of  1 )o  of  ha^Agi^  .^ol. 
observation, - 

ihe  gases  from  the  both  electrodes, 
no  precipitation. 

iiixperiment  2. 

--fter  15  minutes  of  electrolysis  of  the  experiment 
1,5  grams  of  sodium  arsenate  is  added. 

j-he  observation  and  the  results  are  the  same. 

experiment  5. 

nfter  15  minutes  of  electrolysis  of  experioient  2, 

5 grams  of  sodium  arsenate  is  added. 

observation,-  Ko  precipitation,  but  slightlty 
cloudy. 

Experiment  4. 

Ihe  filtrate  of  the  experiment  ef  2 is  electrolyzed 
for  15  minutes  after  addition  of  5 grams  of  sodium  arse- 
nate , 

ob..  ervation, - Became  very  much  cloudy. 

.•«eight  of  the  precipitate  obtained  0.1042  gm. 


-16- 


ikperinaent  5. 

^ftei"  15  minutes  of  electrolysis  of  experiment  ’ 4, 
filtered.  i'o  filtrare  5 grams  of  sodium  arsenate  is 

added,  and  electrolyzed. 

ubservation,  - i^o  precipitation. 

Experiment  6 . ^ 

After  15  minutes  of  electrolysis,  10  grams  of 
sodium  arsenate  is  added. 

Eo  precipitation. 

/ 

jSxperiment  7 . 

After  15  minutes  of  electrolysis,  15  grams  of 
sodium  arsenate  is  added. 

bo  changes  from  the  preceding  experiment 
observed.  ^ 

Summary  for  the  experiment  series  2. 

■fhe  small  amount  of  precipitation  vv^as  obtained  in 
experiment  3 and  4,  vvhose  concentrations  are  3 and  4 respeclr 
ively . 


-17- 


1 bEi\Ixj3  3, 

The  effect  of  the  varying  proportion  and  the 
concentrations  of  the  electrolyte  and  of  the  secondary 
salts  is  determined. 

The  fixed  conditions  are  the  same  with  series 
1 experiment. 

The  quantity  of  electrolyte  taken  in  each  exp- 
eriment is  500  CC. 

The  electrolyte  was  kept  in  acidic  codition 
with  nitric  acid  and  indicator,  in  order  to  prevent 
the  formation  of  basic  lead  salt. 

iiir  is  bubbled  through  the  electrolyte  in 
order  to  stir  the  precipitates  formed. 

Experiment  1. 

electrolyte,-  2pts  of  S of  sodium  arsenate. 

3 “ "5  " ” pottasium  chlorate. 

observation, - 

Voltage  drop, -5.0  v.  initial,  o,S  v.  final, 
hydrogen  gas  from  the  cathode  and  precipitat 
cling  to  the  anode. 

.weight  of  precipitate  obtained  after  30 
minutes  of  run,  2.3830  gm. 

experiment  2. 

Electrolyte,-  2 pts.  of  of  sodium  arsenate. 

3 " “5  /u  " pottasium  chlor- 


• ■ o'  .'  -'*■'  f ' .*‘  -,  .:•  ’ ^ ‘jI  > ^5^' *'  ■' 

V-*’*'  O’  TjJk'-  ow^hmK. 


. ■ ','  •■■  .V .';.  •■. .! Jh  "2^  ■ 

■■'■••  ' -^  ■ ' *^'  ft  j >■  . . ' ■ '-tM  Og 

•■■=^^.<'  ■•■  #- M''  [ 


O.--  :'. 


i.^^S  ..® 


«,  ^ 


>•  r*"  »■ 


fc.  ► r*"  »■ -,  , • .’•a.:  ' 


-V 


rj  . k 

.'l: 


■ A. 


V-...^>A- 

^ JlmK 

■■■  ' 1.'^:- 


o--.. , ' ..  . f ; :-.  - 

t jj' . It  '•(,& 

SL_ij>v..  ■ • •-■  ..■i.L.x^ : V4' 


► J' 

' t ' 


: M -M 


?$a , . ■?f(  ■-•  f 

>■  • '>v  w)  ^ -•  *irj«»wi  » 


■ '>v  l|M  ^ i*  '■  jtf?l 

'•' • 'j;  ,; 


.1 


Si 


t ■ 


I 1 


'K-sje«M- 


' '^''' 

• y.J!,'  • . 

*■  •'] 

r-j: 


:U:?<  ■'!  - ,!v 


%rf 

I ' 


■ .•  ( ' . .,.'*  •«\Lw*i  ■ * ‘ ‘ ■ ■■'♦  4tf  ' fit 


<4pt>yir9 


-18- 


ate « 

Voltage  drop,-  initial  ^.8  v.  final  5.£  v. 
Wt . of  precipitation  obtained,  3.7825  gni. 


j-ixperiment  5. 

i^lectrolyte  ,-  2 pts . of  10  )o  gol.  of  sodium  arsenate. 

5 ”5  ” ” "-t—  clilorate. 

Voltage  drop,-  initial  4,7  V.  final  6.8  v. 

V/eight  of  precipitation  , 2.7  572  gm. 

experiment  4.  Ohanging  the  concentration  of  n-chlorate. 

Electrolyte, -t  2 pts.  of  2>1o^  Of  n-  chlorate. 

I 3”  " ” 5 " " sodium  arsenate. 

Voltage  drop,-  rnitial  7.0  v.  final  7.9  y. 

weight  of  precipitate  obtained  , 2.0  876  gm. 

Experiment  5. 

Electrolyte,-  I 2 pts.  of  6 E of  n-chlorate. 

I3  ” "5  " " Eodium  arsenate. 

initial  voltage  ^rop,  4.9  y.  , final  5.5  y. 

v.eight  0-  precipitate  obtained,  2,2564  gm. 

Experiment  6, 

Electrolyte,-  I 2 pts.  of  10  Of  h-  chlorate. 

15  •’  ” 5 > " sodium  arsenate. 

Initial  voltage  drop  4.9  v.,  final  5.5  v. 

i/eight  of  precipitate  obtained  2,3605  gm. 


-19- 


iiixperiment  7.  increasing  amount  oi  i^-  clilorcite. 

illectrolyte , - 1 Spts.  oi  10  'jo  of  chr  orate. 

(2  " ” 5 ” sodium  arsenate. 

Voltage  drop,  initial  8.2  v. , final  8.6  v. 

./ei^ht  of  precipitation  obtained  5. 6542  gm. 

i^xperiment  8 . 

-Electrolyte  t 4 pts.  or  10  of  -S-  -clilorate  sol. 

I 1 " “ 5 '■  " sodium  arsenate. 

voltage  drop,-  initial  2.6  v.  , linal  «i>.6  v. 

..eight  of  precipitate  1.5582  gm. 


EULlIAxvY  pa. 

. IKE 

EAPEi.ILIElvi' 

s El  k 1 iii  kj  if  3 

• 

iJxp. 

hlectro-  Oonc. 
lyte . 

Eroport . 

Voltage 
init . 

drop, 
linal.  ' 

5t . of  ppt. 

1. 

1 Ua^AsO^ 
( h CIO3 

"d^/o 
5 “ 

2 pts. 
5 " 

5.0 

6 .3 

2.3820  gm 

2. 

1 lias  -^s 
(h  C1O3 

6 

5 

2n  Ets  . 
5 

3.8 

5.2 

5.7825  " 

5 . 

( i'ia3  .‘.^s  • 0^ 
( n 010^ 

10 
5 '■ 

Cj  p>t  S . 

4.7 

5.8 

2.7572  " 

4. 

1 JiCl  L| 
(lJa3As 

5 /J 

5 •' 

2 " 

5 ■■ 

7.0 

7.9 

2.0876  " 

5. 

[ X-  01. 3 

6 >0 
5 " 

2 pts 
5 

. 4.7 

5.9 

2.2564 

6 . 

1 ir  01 C3 
(hajAso^ 

lo  P 
5 " 

2 pts . 

rr  1 - 

0 

4.9 

5 . 5 

2.3605 

7 . 

1 A Cl  O3 
(IIe^xsO^ 

lo 

5 " 

3 i>ts 
2 " 

. 8.2 

8.6 

3.6542 

8. 

IACIO3 

10  '^  0 

4 pts 

2.6 

5.  6 

1.3382 

-20- 


■iU/i  ^ jCi-fc  X b X j-j 

■■i.’'he  e:^Lperiment  Vvc  s done  , using  th.e  method  of 
Vreeland's  patent. 

870,915  I 1908J 

he  u.  ed  a cathode  of  iron  in  a solution  of  alkaline 
hydrozide  contained  ij.  a porou.s  receptacle,  uhich  in  turn 
vv-as  placed  ir  a vessel  containing  an  anode  of  lead  and  a 
solution  of  a salt  v;hieh  v;hen  electrolyzed  vill  produce  a 
soluble  lead  salt.  ^-ead  aricenate  is  formed  by  means  of 

a soluble  s.ult  o:  arsenic. 

fhe  reactions  involves  iij  the;  reactions  are 

x-a"^  goes  into  the  cathode__ ^ i.a  + 0 

i-a  reacts  with  the  water  — yh^-t  '-h 

-b  x.Oj  by  electrolysis — ^ ^^b'^  + 1X3 
fo  the  above  solution  sodium  ^ rsen-  te  ie  added, 
i'b  IhOj  s " . 

fliio  sodium  t.nd  nitrate  are  again  used  as  anode 
solution  in  the  next  operation.  rhis  xrocess , therefore , 

is  simply  the  electrolytic  p eduction  of  lead  nitrate. 

fhe  conditions  fixed  for  the  ■■•xporiaient  are 

-electrolyte  , -rahO  in  anode  and  in  eatiiodc 

comT'^c^rtments . 

Concentration,-  5 per  cent  solution  of  ei^cli. 
-.lectrodes  , - 1 ^-node,-  o-o;..  d plate  who-o  area 

{ L.'vj  Sg. 

I 

(cathode,-  xron  bar  .■vhose  area  1.7 


ar.i . 


j • J.  "V  f ^ 


V 4 / ^ , V • ‘ • /■  f ’ • A ' <■  1 • ^ iBii 

V J.  ' '’  M-, , •*  M ^ • ' • ' ■■  4" 

^ 4 ■#  . ■ V ‘ ^ -tv*  . >■  'l^-' 

,'  ^ •'  , •;?,  *v^  lU '>  ^'  ■ .Vf'i  *^ii  • ‘ IfjUl 


■S.'  I 


T *'  i' 

k. 


ii.)*; : 1 , -f.i  ff.  .Ji  ■ I . ■• 


* ' ‘ • ».  ■*/?!<«  jk-'  ■l>-  fV.Vr4^, 

■ . , .'  : 1.  !v:<  V,i  ’'■'  ' ’’.  ® V ‘''  ? 

■'  ■ ; *.^  ..•/"•■'WdEl/’J  iS’i  • 

*<i*  •.  / I'/A’ **  -'i^.  r '■' ’i?  -'  '^SoPfedli 


. 


■ *'.  I "''»l,<f  '.  .'>  li  ^ -'  J/  ' ^ Y *•*  •■  •>j-’i'l|  f'**  |k' P ''#4^  **■!  * '^Pl- 

• V.  . ' u > . . . - li.i.  A-  *-(  ■ A I - •?'  /!**^*^'  7,’ 

' 4(  M ;,'  ..'Sg 


^ « 'mC  'y'  ’'  t~  ' -,’ vaSI'V  '■■‘.'.V  V?t»'  ’"'  '■  .'if  f.'i^  ■‘'i  .'V 


•: :MfX. yii»  y' -*fJ9K4 '.■j!* 

, . ■?'  'jti  1,  i ' ' !f  . ( . *1'.  , < 4' 


Vtl 


-21- 


Liurrent  o.eiisity,-  0.5ci.  amp,  per  sq.  dm. 

Duration  oi  run,-  30  minutes, 
rafter  tlie  i-un  in  each  experiment,  10  percent  solution 
of  sodium  arsenate  is  added  until!  the  solution  is  salsurated 
and  teh  solution  is  filtered,  the  precipitate  then  dried 
and  weighed. 

iiixperiment  1. 

500  Of  5 percent  of  sodium  nitrate  solution  is 
taken • 

.^eig,ht  of  the  precipitate  obtained--?  .3167'  gm. 
i^pE  riment  2.  ' 

'fhe  filtrate  from  the  experiment  1 is  again  electro- 
lyzed for  30  minutes , and  saturated  with  sodium  arsenate, 
the  precipitate  Vvas  filtered  and  neighed. 

uei,  ht  of  ppt.--  10. 176 5 gm. 

« 

Experiment  3. 

■ihe  filtrate  of  experiment  2is  electrolysed,  and 
the  precipitatev;as  w-eighed. 

weight  of  precipitate — 10.6382  gm. 

Th.e  process  goes  indefinitely  by  addition  of 
sodium  arsenate,  the  weights  of  precipitate  obtained  aie 
7.2167  gm.  , 10.1765  gm.,  and  10.6382  gm.respec tively . 


ju  iiiXt  -L  ^ j-j  - fc  Xi-*  5 • 

I'he  effect  o^.  various  catliodes  vas  examined, 
file  fixed  c ond  i t i ons  a r e 

Electrolyte,-  5 per  cent  of  sodium  arsenate, 
current  density, -0.5  amp.  sg.  dm. 
l>urration  of  run,-  20  minutes. 

Ex  p e r imen t 1 . 

nlectrode  used,-  lEad  catliode  liaving  area  of  2.3  sq.  dm. 
Voltage  drop,-  initial  6.8  v.,  final  6.4  v. 

./eiglit  of  precipitate,-  1.8226  gm. 

Experiment  2. 

x^lectrode, - Liarbon  -whose  solution  area  o.74  sq.  dm. 
Electrode  portential,-  initial  9,0  , final  8.6  v. 

..eight  of  precipitate,-  4.Y858  gm. 

Experiment  5. 

electrolyte,-  copper  plate  vdiose  area  1.7  sq.  dm. 
electrode  portential,-  initial  9.0,  final  8,6  v. 
weight  of  precipitate,-  5.0'. 42  gm. 

Experiment  4. 

Electrode,-  iron  rod  nhOoe..  electrode  area  being 
0.7  sq.  dm. 

Electrode  portential,-  initial  12.0  v.  rinal  10,8  v. 


./eight  of  precipitate  obtained,-  1.5350  gm. 


u]?  ' 5. 


Carbon  electrode  gave  the  best  yield  and  copi-er  also 
hi  fx  value  under  the  given  condition.  iron  and  lead 
gave  very  lov  value. 


1.  ii^luenceB  of  different  el^-ctrodes  for  the  pre- 

cipitation. 

und(  rthe  same  condition,  b y changing  electrode, 
variable  precipitate  was  obtainedas  sho..n  in  the  er^eii- 
ment  series  6. 

2.  i^iffect  of  change  concentration  in  the  electrolyte. 

There  is  an  optinum  concentration  for  the  precip- 
tation  under  each  condition.  The  conditions  may  in-, 

elude  current  density,  various  cathodes,  nature  of  electroly 
tempreture  of  the  bath  and  Some  others. 

onder  the  condition  o experiment  series  2,  the 
conc' ntration  of  S or  4 percent  was  found  as  the  best 
suited. 


5.  rnfluence  of  the  secondary  salts. 

As  to  the  possible  explanation  of  the. function  of 
secondary  salt  presented, 

a.  ihe  presence  of  the  secondary  salt  increases 

the  conductivity  of  theelectr olyte  . 


D . 


■fliis  in  turn  acceleratesthe  speed  of  lead 


going  into  the  ionic  form. 

c.  'The  ionized  lead  will  o^uickly  take  up  arsenate 

ion  forming  insoluble  lead  arsenate. 


3 


-25- 


d.  This  conseauently  increases  the  dissociation 
of  .:odiiiai  arsenate  used. 

e.  As  inference,  the  secondary  salt,  therefore, 
should  be  highly  ionisable  salts. 

4.  The  use  of  soluble  salts  of  arsenate. 

ns  industrial  process  the  use  of  soluble  salts 
of  arsenate  is  seems  to  me  impossible,  owing  to  the  high 
cost  of  arsenate  salt.  i5y  this  very  reason  Vreeland,  the 

inventor  of  electrolysis  method,  has  abondoned  his  proerss 
as  soon  as  the  other  process,  which  use  cheaper  ravv  material 
for  the  manufacture  of  lead  arsenate .came  into  enistence. 

As  ascientific  investigatio  n this  is  an  interesting 
subject.  The  sturdy  may  lead  to  establish  some  theories 

which  may  be  applicable  to  similar  reactions. 

The  use  of  cheaper  raw  materials,  such  as  white  arse- 

t 

nic , litharge,  minium,  or  galena  is  essential  .or  the  develo 
merit  of  lead  arsenate  industry.-  from  this  standpoint, 

it  may  be  well  to  investigate  on  electrolysis  of  fused  white 
ar;  enic  and  lead  salts.  ur  it  may  be  advantagious  to 

pass  electric  current  through  mf?:ed  vapor  phases,  as  these 
arsenic  and  lead  salts  are  easily  sublimed  at  a fairly 


low  temperature 


